Friction modifier for hydrocarbon fuels

ABSTRACT

There is provided a friction modifier of the formula R 1 L-N(R 2 )(R 3 ) wherein R 1  is a hydrocarbyl group that has a number average molecular weight (Mn) of from 500 to 5000; L is an optional linker group; and R 2  and R 3  are independently selected from H, a hydrocarbyl group and a bond to optional group L, wherein at least one of R 2  and R 3  is H or a hydrocarbyl group, with the proviso that if one of R 2  and R 3  is a hydrocarbyl group and the other of R 2  and R 3  is H, the hydrocarbyl group does not contain a terminal amine.

This invention relates to multifunctional friction modifiers and friction modifying compositions for hydrocarbon fuels, especially gasoline. In particular, the invention relates to alkenylsuccinimide-based friction modifiers and friction modifying compositions for hydrocarbon fuels and especially gasoline.

It has been of major concern in this field to find methods of reducing engine friction and fuel consumption in internal combustion engines. It is believed that by reducing engine friction, increased power and fuel economy may be obtained. One method of reducing engine friction is to use fuel which has been dosed with an additive having friction reducing properties.

Additive compositions for gasoline have to satisfy a large number of criteria, amongst the most important of which are:

-   i) reduction of engine friction to increase fuel economy; -   ii) good lubrication to reduce wear; -   iii) elimination of carburettor and injector fouling; -   iv) good detergency in the intake port and intake valve regions of     the engine; -   v) elimination of valve stick, a problem often associated with the     use of high molecular weight detergents; -   vi) corrosion protection; -   vii) good demulsifying characteristics.

In order to meet these criteria, it has been necessary until now to provide additive packages comprising a separate friction modifier and detergent/deposit inhibiting compound. For example, WO-A-98/11175 discloses an additive package comprising an ashless friction modifier, a deposit inhibitor and a carrier fluid. As discussed in WO-A-98111175, current practice in the supply of gasoline is generally to pre-mix the fuel additives into a concentrate in a hydrocarbon solvent base, and then inject the concentrate into gasoline pipelines used to fill tankers prior to delivery to the customers. Under present operating conditions, the maximum amount of concentrate that can be incorporated into a tanker of gasoline is typically about 2000 ppm based on the weight of the gasoline. It would appear that in order to avoid exceeding this maximum amount of additive, the provision of multifunctional fuel additives would be advantageous.

WO-A-93/20170 discloses a composition comprising succinimide detergents and mono end-capped polypropylene glycol. Each of the specifically disclosed detergents is derived from a polyalkylene polyamine comprising two primary amine groups. The resultant succinimide detergent comprises a terminal amine group.

Some aspects of the present invention are defined in the appended claims.

In a first aspect the present invention provides a friction modifier of the formula R¹-L-N(R²)(R³) wherein R¹ is a hydrocarbyl group and has a number average molecular weight (Mn) of from 500 to 5000; L is an optional linker group; R² and R³ are independently selected from H, a hydrocarbyl group and a bond to optional group L, wherein at least one of R² and R³ is H or a hydrocarbyl group, with the proviso that if one of R² and R³ is a hydrocarbyl group and the other of R² and R³ is H, the hydrocarbyl group does not contain a terminal amine.

In a second aspect the present invention provides a friction modifying composition comprising a friction modifier as herein defined and a carrier oil comprising an optionally esterified polyether.

It has surprisingly been found that these new friction modifiers and friction modifying compositions are multifunctional and exhibit, in addition to their friction modifying characteristics, good intake valve detergency, good valve stick performance and good packagability. The multi-functional nature of the friction modifiers and friction modifying compositions according to the present invention enables them to be used in the substantial absence of any additional friction modifier or detergent. This is advantageous, for example, because of the need to conform to limits on the amount of fuel additive incorporated into fuel.

Use of these new friction modifiers and friction modifying compositions in fuel in a combustion engine, may result in a considerable reduction in friction and wear, in particular a reduction in wear in the fuel pump and around the piston walls of the combustion engine. The reduction in friction should result in improved fuel economy. Wear of components of a combustion engine limits the useful life of these components and may be costly given that the engine components are expensive to produce. Additionally, wear of components of a combustion engine may result in down time for equipment, reduced safety and a decrease in reliability. Use of the friction modifiers or friction modifying compositions according to the present invention may reduce wear increasing the lifetime of the combustion engine components and thus avoiding the problems associated with wear. These friction modifiers and friction modifying compositions may also be of benefit in gasoline direct injection engines (GDI).

In the present application by the term “friction modifier” it is meant a substance capable of modifying friction. In particular, by the term “friction modifier” it is meant a substance capable of reducing friction. In particular, the term “friction modifier” refers to a substance which is capable of reducing friction, when dosed into a fuel which is subsequently combusted in a combustion engine.

In one aspect, the term “friction modifier” refers to a substance which, at a treat rate of 120 mg/l in unleaded gasoline generates a Wear Scar Diameter in the High Frequency Reciprocating Rig test at 20° C. of less than 500 microns, preferably less than 450 microns, more preferably less than 400 microns.

In the present specification by the term “hydrocarbyl group” it is meant a group comprising at least C and H and may optionally comprise one or more other suitable substituents. Examples of such substituents may include alkoxy-, nitro, a hydrocarbon group, an N-acyl group, a cyclic group etc. In addition to the possibility of the substituents being a cyclic group, a combination of substituents may form a cyclic group. If the hydrocarbyl group comprises more than one C then those carbons need not necessarily be linked to each other. For example, at least two of the carbons may be linked via a suitable element or group. Thus, the hydrocarbyl group may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for instance, nitrogen and oxygen.

Friction Modifier—R¹

Preferably R¹ is a hydrocarbon group. By the term “hydrocarbon group” it is meant a group comprising only C and H. The hydrocarbon group may be saturated or unsaturated. The hydrocarbon group may be straight chained or branched.

Preferably R¹ is a branched or straight chain alkyl group. More preferably R¹ is a branched alkyl group.

In a particularly preferred embodiment R¹ is polyisobutene.

Conventional and so called high reactivity polyisobutenes are suitable for use in the invention. High reactivity is defined as a polyisobutene wherein at least 50%, preferably 70% or more of the terminal olefinic double bonds are of the vinylidene type.

The preparation of polyisobutenyl substituted succinic anhydrides (PIBSA) is documented in the art. Suitable processes include thermally reacting polyisobutenes with maleic anhydride (see for example U.S. Pat. No. 3,361,673 and U.S. Pat. No. 3,018,250), and reacting a halogenated, in particular a chlorinated, polyisobutene (PIB) with maleic anhydride (see for example U.S. Pat. No. 3,172,892). Alternatively, the polyisobutenyl succinic anhydride can be prepared by mixing the polyolefin with maleic anhydride and passing chlorine through the mixture (see for example GB-A-949,981).

The reaction product of these processes will be a complex mixture of unreacted polymer as well as the product polyisobutenyl succinic acid anhydride, the polyisobutenyl substituent being connected to either one or both of the alpha carbon atoms of the succinic add group.

R¹ may have a molecular weight selected to provide the required properties of the detergent compound. In a preferred aspect R¹ has a molecular weight of from 800 to 1300. In a particularly preferred aspect R¹ is polyisobutene having a molecular weight of from 800 to 1300. The molecular weights are as determined by vapour phase osmometry or by gel permeation chromatography, on the originating polymer.

In one aspect R¹ may have from 10 to 200 carbons or from 10 to 100 carbons.

Friction Modifier—Linker

The friction modifier of the formula R¹-L-N(R²)(R³) may or may not comprise optional linker L. If L is present it may be any suitable group. Suitable groups include

-   -   C₁₋₆ hydrocarbyl groups optionally including one or more,         preferably two, carbonyl groups,     -   C₁₋₆ hydrocarbon groups optionally including one or more,         preferably two, carbonyl groups,     -   C₃₋₁₂diacyl groups which when bonded to N(R²)(R³) provides a         cyclic group of formula:         wherein e and f are independently an integer of from 0 to 6.     -   diacyl groups derived from succinic anhydride which when bonded         to N(R²)(R³) provides a cyclic group of formula:         wherein e is 0 and f is 1 .         Friction Modifier—N(R²)(R³)

The friction modifier of the present invention contains a nitrogen moiety N(R²)(R³) attached to the hydrocarbyl group R¹ via optional linker L. The groups and R² and R³ of the nitrogen moiety are independently H or a hydrocarbyl group. Thus

-   -   both R² and R³ may be H     -   one of R² and R³ may be H and the other of R² and R³ may be         hydrocarbyl     -   both of R² and R³ may be hydrocarbyl.

R² and R³ are independently selected from H, a hydrocarbyl group and a bond to optional group L, wherein at least one of R² and R³ is H or a hydrocarbyl group. When one of R² and R³ is a bond to optional group L, the nitrogen may contain either a double bond to a single atom of the group L or may be bonded to two different moieties of group L to form a cyclic group. Clearly if optional group L is not present these explanations equally apply to the connection between R¹ and N(R²)(R³).

It is requirement that when one of R² and R³ is a hydrocarbyl group and the other of R² and R³ is H, the hydrocarbyl group does not contain a terminal amine. In other words when one of R² and R³ is a hydrocarbyl group and the other of R² and R³ is H, if the hydrocarbyl group is an amine or polyamine the amine or amine units are selected from secondary and tertiary amines.

Suitable terminal groups include —CH₃, ═CH₂, —OH, —C(O)OH and derivatives thereof. Suitable derivatives include esters and ethers.

Preferably the hydrocarbyl group R² and/or R³ does not contain a terminal amine. In other words if R² and/or R³ is a hydrocarbyl group selected from an amine or polyamine, the amine or amine units are selected from secondary and tertiary amines.

A preferred hydrocarbyl group for each of R² and R³ is a group of the formula —[R⁴NH]_(p)R⁵X

-   wherein R⁴ is an alkylene group having from 1 to 10 carbons,     preferably from 1 to 5, preferably 1 to 3 carbons, preferably 2     carbons; -   wherein R⁵ is an alkylene group having from 1 to 10 carbons,     preferably from 1 to 5, preferably 1 to 3 carbons, preferably 2     carbons; -   wherein p is an integer from 0 to 10; -   wherein X is selected from —CH₃, —CH₂═CH₂, —OH, and —C(O)OH.

A preferred hydrocarbyl group for each of R² and R³ is a group of the formula —[(CH₂)_(q)NH]_(p)(CH₂)_(r)X

-   wherein p is an integer from 0 to 10, preferably 1 to 10, preferably     from 1 to 5, preferably from 1 to 3, preferably 1 or 2; -   wherein q is an integer from 1 to 10, preferably from 1 to 5,     preferably from 1 to 3, preferably 1 or 2; -   wherein r is an integer from 1 to 10, preferably from 1 to 5,     preferably from 1 to 3, preferably 1 or 2; and -   wherein X is selected from —CH₃, —CH₂═CH₂, —OH, and —C(O)OH.

Preferably X is —CH₃, or —OH.

The friction modifiers of the present invention may be derived from a wide range of precursors. Embodiments of the present invention include compounds derived from amines selected from ammonia, butylamine, aminoethylethanolamine, aminopropan-2-ol, 5-aminopentan-1-ol, 2-(2-aminoethoxy)ethanol, monoethanolamine, 3-aminopropan-1-ol, 2-((3-aminopropyl)amino)ethanol, dimethylaminopropylamine, and N-(alkoxyalkyl)-alkanediamines including N-(octyloxyethyl)-1,2-diaminoethane and N-(decyloxypropyl)-N-methyl-1,3-diaminopropane.

The features described above may provide particularly preferred compounds in accordance with the present invention. These include compounds wherein

-   -   at least one of R² and R³ is a group of the formula —(CH₂)₃CH₃;     -   one of R² and R³ is a group of the formula —(CH₂)₃CH₃, and the         other of R² and R³ is H;     -   at least one of R² and R³ is a group of the formula         —(CH₂)₂NH(CH₂)₂OH;     -   one of R² and R³ is a group of the formula —(CH₂)₂NH(CH₂)₂OH,         and the other of R² and R³ is H; and     -   the friction modifier is a polyisobutenyl succinimide.

In one preferred aspect the friction modifier of formula R¹-L-N(R²)(R³) comprises the optional linker L, and L, when bonded to N(R²)(R³), provides a cyclic group of formula:

wherein e and f are independently and integer from 0 to 6. In this aspect, R³ is preferably a hydrocarbyl group.

In one aspect R³ is a hydrocarbyl group of formula: —[R⁴NH]_(p)R⁵—N(R^(2′))-L′-R^(1′)

-   wherein R^(1′) is a hydrocarbyl group and has a number average     molecular weight (Mn) of from 500 to 5000; -   wherein L′ is an optional linker group; -   wherein R^(2′) is independently selected from H, a hydrocarbyl group     and a bond to optional group L′; -   wherein R⁴ is an alkylene group having from 1 to 10 carbons,     preferably from 1 to 5, preferably 1 to 3 carbons, preferably 2     carbons; -   wherein R⁵ is an alkylene group having from 1 to 10 carbons,     preferably from 1 to 5, preferably 1 to 3 carbons, preferably 2     carbons; and -   wherein p is an integer from 0 to 10.

In a preferred aspect R³ is a hydrocarbyl group of formula: —[(CH₂)_(q)NH]_(p)(CH₂)_(r)—N(R^(2′))-L′-R^(1′)

-   wherein R^(1′) is a hydrocarbyl group and has a number average     molecular weight (Mn) of from 500 to 5000; -   wherein L′ is an optional linker group; -   wherein R^(2′) is independently selected from H, a hydrocarbyl group     and a bond to optional group L′; -   wherein p is an integer from 0 to 10, preferably 1 to 10, preferably     from 1 to 5, preferably from 1 to 3, preferably 1 or 2; -   wherein q is an integer from 1 to 10, preferably from 1 to 5,     preferably from 1 to 3, preferably 1 or 2; and -   wherein r is an integer from 1 to 10, preferably from 1 to 5,     preferably from 1 to 3, preferably 1 or 2.

Preferably R^(1′) is a hydrocarbon group. Preferably R^(1′) is a branched or straight chain alkyl group. More preferably R^(1′) is a branched alkyl group. In a particularly preferred embodiment R^(1′) is polyisobutene.

R^(1′) may have a molecular weight selected to provide the required properties of the friction modifier. In a preferred aspect R^(1′) has a molecular weight of from 800 to 1300. In a particularly preferred aspect R^(1′) is polyisobutene having a molecular weight of from 800 to 1300. The molecular weights are as determined by vapour phase osmometry or by gel permeation chromatography, on the originating polymer.

In one aspect R^(1′) may have from 10 to 200 carbons or from 10 to 100 carbons.

If L′ is present it may be any suitable group. Suitable groups include

-   -   C₁₋₆ hydrocarbyl groups optionally including one or more,         preferably two, carbonyl groups,     -   C₁₋₆ hydrocarbon groups optionally including one or more,         preferably two, carbonyl groups,     -   C₃₋₁₂ diacyl groups which, when R^(2′) is a bond to group L′,         provide a cyclic group of formula:         wherein e′ and f′ are independently an integer of from 0 to 6.     -   diacyl groups derived from succinic anhydride which, when R^(2′)         is a bond to group L′, provide a cyclic group of formula:         wherein e′ is 0 and f′ is 1.         Friction Modifying Composition—Carrier Oil

As previously mentioned, in one aspect the present invention provides a friction modifying composition comprising a friction modifier as herein defined and a carrier oil comprising an optionally esterified polyether.

The carrier oil may have any suitable molecular weight. A preferred molecular weight is In the range 500 to 5000.

In a preferred aspect the polyether carrier oil is a mono end-capped polypropylene glycol. Preferably the end cap is a group consisting of or containing a hydrocarbyl group having up to 30 carbon atoms. More preferably the end cap is or comprises an alkyl group having from 4 to 20 carbon atoms or from 12 to 18 carbon atoms.

The alkyl group may be branched or straight chain. Preferably it is a straight chain group.

Further hydrocarbyl end capping groups include alkyl-substituted phenyl, especially where the alkyl substituent(s) is or are alkyl groups of 4 to 20 carbon atoms, preferably 8 to 12, preferably straight chain.

The hydrocarbyl end capping group may be attached to the polyether via a linker group. Suitable end cap linker groups include an ether oxygen atom (—O—), an amine group (—NH—), an amide group (—CONH—), or a carbonyl group —(C═O)—.

In a preferred embodiment the carrier oil is a polypropyleneglycol monoether of the formula:

where R⁶ is straight chain C₁-C₃₀ alkyl, preferably C₄-C₂₀ alkyl, preferably C₁₂-C₁₈ alkyl; and n is an integer of from 10 to 50, preferably 10 to 30, more preferably 12 to 20.

Such alkyl polypropyleneglycol monoethers are obtainable by the polymerisation of propylene oxide using an aliphatic alcohol, preferably a straight chain primary alcohol of to 20 carbon atoms, as an initiator. If desired a proportion of the propyleneoxy units may be replaced by units derived from other C₂-C₆ alkylene oxides, e.g. ethylene oxide or isobutylene oxide, and are to be included within the term “polypropyleneglycol”. The initiator may also be a phenol or alkyl phenol of the formula R⁷OH, a hydrocarbyl amine or amide of the formula R⁷NH₂ or R⁷CONH, respectively, where R⁷ is C₁-C₃₀ hydrocarbyl group, preferably a saturated aliphatic or aromatic hydrocarbyl group such as alkyl, phenyl or phenalkyl etc. Preferred initiators include long chain alkanols giving rise to the long chain polypropyleneglycol monoalkyl ethers.

In a further aspect the polypropyleneglycol may be an ester (R⁶COO) group where R⁶ is defined above. In this aspect the carrier oil may be a polypropyleneglycol monoester of the formula

where R⁶ and n are as defined above and R8 is a C₁-C₃₀ hydrocarbyl group, preferably an aliphatic hydrocarbyl group, and more preferably C₁-C₁₀ alkyl. Friction Modifying Composition—Composition

The friction modifier may be present in the friction modifying composition in an amount to provide the necessary and/or required handling and/or functional properties. Typically the friction modifier (including solvent of production) is present in an amount of from 10 to 60% by weight, preferably 30 to 60% by weight, based on the total composition. Typically the friction modifier (excluding solvent of production) is present in an amount of from 6 to 36% by weight, preferably 18 to 36% by weight, based on the total composition.

The carrier oil may be present in an amount of from 10 to 40% by weight, based on the total composition.

The weight ratio of active friction modifier to carrier oil in the friction modifying composition may be from 0.2:1 to 5:1.

Preferably the weight ratio of active friction modifier to carrier oil in the friction modifying composition will be in the range 0.2:1 to 5:1, or 0.6:1 to 5:1, typically about 5:1, 2:1, 1:1, 0.9:1, 0.8:1, or 0.6:1.

Preferably the weight ratio of active friction modifier to carrier oil in the friction modifying composition will be in the range 1:0.2 to 1:1.8, or 1:0.3 to 1:1.7, or 1:0.4 to 1:1.6, or 1:0.5 to 1:1.5, or 1:0.6 to 1:1.4, or 1:0.7 to 1:1.3, or 1:0.8 to 1:1.2 or 1:0.9 to 1:1.1, typically approximately 1:0.2, 1:0.5, 1:0.7, 1:1, 1:1.1, 1:1.2 or 1:1.6, such as 1:1.

In a preferred aspect the friction modifying composition of the present invention further comprises a solvent. The solvent may be a hydrocarbon solvent having a boiling point in the range 66 to 320° C. Suitable solvents include xylene, toluene, white spirit, mixtures of aromatic solvents boiling in the range 180° C. to 270° C. (including aromatic solvent mixtures sold under the trade marks Shellsol AB, Shellsol R, Solvesso 150, Aromatic 150), and environmentally friendly solvents such as the low aromatic content solvents of the FINALAN range.

If present the amount of solvent to be incorporated will depend upon the desired final viscosity of the friction modifying composition. Typically the solvent will be present in an amount of from 20 to 70% of the final composition on a weight basis.

In a preferred aspect the friction modifying composition of the present invention comprises a solvent and a co-solvent. The co-solvent may be typically present in an amount of 1-2 wt. %. Suitable co-solvents include aliphatic alcohols (such as CAS no 66455-17-2)

The friction modifying compositions of the present invention may contain a number of minor ingredients, often added to meet specific customer requirements. Included amongst these are dehazers, usually an alkoxylated phenol formaldehyde resin, added to minimise water adsorption and to prevent a hazy or cloudy appearance, and a corrosion inhibitor, usually of the type comprising a blend of one or more fatty acids and amines. Either or both may be present in the compositions of the present invention in amounts ranging from 1 to 5%, or 1 to 3% each, based on the total weight of the composition.

Other minor ingredients which may be added include anti-oxidants, anti-icing agents, metal deactivators, dehazers, corrosion inhibitors, dyes, lubricity additives, additional friction modifiers, and the like. These may be added in amounts ranging from a few parts per million, up to 2 or 3% by weight, according to conventional practice.

In one preferred aspect, no lubricity additives or friction modifiers other than the friction modifier as herein defined are added to the friction modifying composition.

In general terms the total amount of such minor functional ingredients in the friction modifying composition will not exceed about 10% by weight, more usually not exceeding about 5% by weight.

Fuel Additive Composition

In one aspect the present invention provides a fuel additive composition comprising a friction modifier as herein defined and a carrier, diluent or solvent, wherein the fuel additive composition is substantially free of any detergent and/or friction modifier other than the friction modifier as herein defined.

The term “fuel additive composition” as used herein refers to a composition which will undergo no modification before it is dosed into a fuel. In particular the term refers to a composition to which no further components are added before it is dosed into a fuel.

The term “substantially free” of a given substance, as used herein in relation to a fuel additive composition, means that the substance is present in the fuel additive composition in an amount of less than 1% by weight of the composition, preferably less than 0.5%, preferably less than 0.1%, preferably less than 0.05%.

Preferably the fuel additive composition is substantially free of any detergent other than the friction modifier as herein defined.

Preferably the fuel additive composition is substantially free of any friction modifier other than the friction modifier as herein defined.

Preferably the fuel additive composition is substantially free of any detergent and any friction modifier other than the friction modifier as herein defined.

In a preferred aspect, the carrier, diluent or solvent is a carrier oil comprising an optionally esterified polyether.

Preferably the carrier, diluent or solvent is a polyether carrier oil as herein defined.

Preferably the carrier, diluent or solvent of the fuel additive composition is a polypropyleneglycol monoether of the formula:

where R⁶ is straight chain C₁₂-C₁₈ alkyl; and n is an integer of from 10 to 30. Fuel Compositions

The friction modifier of the present invention may be incorporated in fuel to provide a fuel composition. Thus in a further aspect the present invention provides a fuel composition comprising a fuel and a friction modifier as herein defined.

The friction modifying composition of the present invention may be incorporated in fuel to provide a fuel composition. Thus in a further aspect the present invention provides a fuel composition comprising a fuel and a friction modifying composition as herein defined.

The fuel additive composition of the present invention may be incorporated in fuel to provide a fuel composition. Thus in a further aspect the present invention provides a fuel composition comprising a fuel and a fuel additive composition as herein defined.

Preferably the friction modifier is present in the fuel in an amount to provide on a weight basis, from 50 to 500 ppm.

Preferably the friction modifying composition is present In the fuel in an amount to provide on a weight basis, from 50 to 500 ppm friction modifier and 30 to 500 ppm carrier oil.

Preferably the fuel composition is substantially free of any detergent other than the friction modifier as herein defined.

Preferably the fuel composition is substantially free of any friction modifier other than the friction modifier as herein defined.

Preferably the fuel composition is substantially free of any detergent other than the friction modifier as herein defined and substantially free of any friction modifier other than the friction modifier as herein defined.

The term “substantially free” of a given substance, as used herein in relation to a fuel composition, means that the substance is present in the fuel composition in an amount of less than 10 ppm, preferably less than 5 ppm, preferably less than 1 ppm.

Preferably the fuel is a gasoline.

By the term “gasoline”, it is meant a liquid fuel for use with spark ignition engines (typically or preferably containing primarily or only C4-C12 hydrocarbons) and satisfying international gasoline specifications, such as ASTM D-439 and EN228. The term includes blends of distillate hydrocarbon fuels with oxygenated components such as ethanol, as well as the distillate fuels themselves. The fuels may contain, in addition to the additive composition of the invention, any of the other additives conventionally added to gasoline as, for example, antiknock additives, anti-icing additives, octane requirement additives, lubricity additives etc.”

It is known that prior to combustion certain fuel additives can reach the thin film of lubricant that coats the cylinder wall and can, over time, accumulate in engine oil. It is therefore envisaged that in one aspect the friction modifier or friction modifying composition accumulates in engine oil. In one embodiment, the present invention provides an oil composition comprising an engine oil and a friction modifier or friction modifying composition as herein defined. In one aspect the present invention provides an oil composition comprising (i) an oil, preferably an engine oil and (ii) a friction modifier of the formula R¹-L-N(R²)(R³) wherein R¹ is a hydrocarbyl group and has a number average molecular weight (Mn) of from 500 to 5000; L is an optional linker group; R² and R³ are independently selected from H, a hydrocarbyl group and a bond to optional group L, wherein at least one of R² and R³ is H or a hydrocarbyl group, with the proviso that if one of R² and R³ is a hydrocarbyl group and the other of R² and R³ is H, the hydrocarbyl group does not contain a terminal amine.

Process

In one aspect the present invention provides a process for the reduction of friction in a combustion engine comprising the steps of (i) dosing a fuel with a friction modifier as herein defined, or a friction modifying composition as herein defined, or a fuel additive composition as herein defined, to provide a fuel composition; (ii) combusting the fuel composition in a combustion engine.

Use

In one aspect the present invention provides use of a friction modifier as herein defined for reducing friction and/or improving detergency in a combustion engine. In one preferred aspect the present invention provides use of a friction modifier as herein defined for reducing friction in a combustion engine. In one highly preferred aspect the present invention provides use of a friction modifier as herein defined for reducing friction and improving detergency in a combustion engine.

In one aspect the present invention provides use of a friction modifying composition as herein defined for reducing friction and/or improving detergency in a combustion engine. In one preferred aspect the present invention provides use of a friction modifying composition as herein defined for reducing friction in a combustion engine. In one highly preferred aspect the present invention provides use of a friction modifying composition as herein defined for reducing friction and improving detergency in a combustion engine.

In one aspect the present invention provides use of a fuel additive composition as herein defined for reducing friction and/or improving detergency in a combustion engine. In one preferred aspect the present invention provides use of a fuel additive composition as herein defined for reducing friction in a combustion engine. In one highly preferred aspect the present invention provides use of a fuel additive composition as herein defined for reducing friction and improving detergency in a combustion engine.

The present invention will now be described in further detail by way of Example only.

EXAMPLES Synthesis of Friction Modifiers

Amine used to Produce Friction Modifier Friction Modifier Ammonia

Butylamine

Aminoethylethanolamine (AEEA)

Tetraethylenepentamine (TEPA)

Example 1 1000 mwt PIBSA & Butylamine

1000 mwt high reactive PIB derived PIBSA (467.6 g) was stirred with Shellsol AB (311.89 ) in a 1 l oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Whilst still at room temperature butylamine (31.5 g) was added in one aliquot with continued stirring. An immediate exotherm was noted. The reaction mix was heated to ˜150° C. for three hours whilst removing water. 720 g of product was isolated

Analysis of the product showed it to contain 40% m/m solvent, 0.81% m/m nitrogen.

Example 2 1000 mwt PIBSA & Aminoethylethanolamine

1000 mwt high reactive PIB derived PIBSA (633.2 g) was stirred with Shellsol AB (421 g) in a 1 l oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Whilst still at room temperature aminoethylethanolamine (60.6 g) was added in one aliquot with continued stirring. An immediate exotherm was noted. The reaction mix was heated to 130-150° C. for three hours whilst removing water. 1058 g of product was isolated.

Analysis of the product showed it to contain 39% m/m solvent, 1.47% m/m nitrogen.

Example 3 550 mwt PIBSA & Aminoethylethanolamine

550 mwt high reactive PIB derived PIBSA in Shellsol AB (900 g, 40% solvent) was stirred in a 1 l oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Aminoethylethanolamine (84.2 g) was added at room temperature whilst stirring. An exotherm was noted. The reaction mix was heated to 140° C. for four hours whilst removing water. 926 g of product was isolated.

Analysis of the product showed it to contain 38.5% m/m solvent, 2.33% m/m nitrogen.

Example 4 2300 mwt PIBSA & Butylamine

2300 mwt high reactive PIB derived PIBSA in Shellsol (495 g, 21.6% solvent) was stirred with extra Shellsol AB (110 g) in a 1 l oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Butylamine (9.37 g)was added at room temperature whilst stirring. The reaction mix was heated to 130° C. for three hours whilst removing water. 645 g of product was isolated.

Analysis of the product showed it to contain 38% m/m solvent, 0.35% m/m nitrogen.

Example 5 2300 mwt PIBSA & Aminoethylethanolamine

2300 mwt high reactive PIB derived PIBSA in Shellsol (508 g, 21.6% solvent) was stirred with extra Shellsol AB (157 g) in a 1 l oil jacketed reactor equipped with an overhead stirrer, thermometer and Dean & Stark trap. Aminoethylethanolamine (17.65 g) was added at room temperature whilst stirring. The reaction mix was heated to 140° C. for 3.5 hours whilst removing water. 838 g of product was isolated.

Analysis of the product showed it to contain 42% m/m solvent, 0.65% m/m nitrogen.

Example 6 1000 mwt PIBSA & Ammonia

1000 mwt high reactive PIB derived PIBSA (450.15 g) was stirred with Shellsol AB (298.99 g) in a 1 l oil jacketed reactor equipped with an overhead stirrer, thermometer, Dean & Stark trap and a dip tube through which to add ammonia. The temperature was taken up to 138° C. and the ammonia gas (5.81 g) was added over 3 hours, whilst collecting water in the trap. Heating was continued for a further 2 hours. 731 g of product was isolated.

Analysis of the product showed it to contain 40% m/m solvent, 0.76% m/m nitrogen.

Test Data

Example 7 High Frequency Reciprocating Rig (HFRR) Test

The standard procedure for evaluating diesel fuel lubricity using the High Frequency Reciprocating Rig (HFRR) test was modified to evaluate gasoline lubricity. A temperature of 20° C., which is lower than the standard temperature, was selected due to the higher volatility of gasoline as compared with diesel.

The procedure was as follows. A steel ball was attached to an oscillating arm assembly and mated to a steel disk specimen in the HFRR sample cell. The fuel reservoir contained 6 ml of the fuel composition being tested. A load of 200 grams was applied to the ball/disk interface by dead weights. The ball assembly was oscillated over a 1000μ path at a rate of 50 Hertz. After a prescribed period of time, the steel ball assembly was removed. Wear, and hence the lubricity of the fuel composition, was assessed by measuring the wear scar diameter on the ball resulting from oscillating contact with the disk. The lower the value of the wear scar diameter the better the performance of the additive in the fuel composition. A wear scar diameter of below 500μ is particularly desirable. The results are set out in the tables below. Total Treat Wear Scar Fuel Composition Rate (mg/l) (microns) Unleaded gasoline basefuel — 824 Unleaded gasoline basefuel + 200 434 bis TEPA PIBSI (1000 mwt) Unleaded gasoline basefuel + 200 376 AEEA PIBSI (1000 mwt) Unleaded gasoline basefuel + 420 321 AEEA PIBSI (1000 mwt) + Polyether Active Ingredient Total Treat Treat Rate Wear Scar Fuel Composition Rate (mg/l) (mg/l) (microns) Unleaded gasoline basefuel 0 0 838 Unleaded gasoline basefuel + 200 120 400 AEEA PIBSI (1000 mwt) Unleaded gasoline basefuel + 156 120 825 ButA PIBamine (1000 mwt) Unleaded gasoline basefuel + 120 120 767 PIB (1000 mwt)

The following table shows the results obtained for commercial gasoline additives and an example of the present invention in this test. The additives were tested at equivalent active treat rates. Fuel composition Wear Scar (microns) Unleaded gasoline basefuel 810 Unleaded gasoline basefuel + 609 commercial Mannich amine Unleaded gasoline basefuel + 699 commercial PIBamine (1) Unleaded gasoline basefue + 743 commercial PIBamine (2) Unleaded gasoline basefuel + 674 commercial Polyetheramine Unleaded gasoline basefuel + 414 AEEA PIBSI

Example 8 Improved Packagebility

Generally friction modifiers such as polyisobutenyl succinimide (PIBSI) and carrier fluids are incompatible without the addition of a suitable solvent. Many packages require additional solvent above the amount already present due to the manufacture of the friction modifier.

A series of packages were produced using a range of carriers and friction modifiers. The following table shows the total percentage of solvent required to keep a 1:1 ratio of active friction modifier and carrier fluid package in one phase at ambient conditions. The lowest solvent content possible in this test is 25-26% due to the solvent associated with the friction modifier manufacture. Amine used to produce friction modifier Aminoethyl- Tetraethylene- Ammonia Butylamine ethanolamine pentamine Carrier A — 26 25 25 Carrier B — 26 25 30 Carrier C 25 26 25 37 Carrier D — 26 30 40

-   Carrier A is a C₁₃₋₁₅ initiated polyether having 12 propylene oxide     units attached -   Carrier B is a C₁₃₋₁₅ initiated polyether having 14 propylene oxide     units attached -   Carrier C is a C₁₃₋₁₅ initiated polyether having 17 propylene oxide     units attached -   Carrier D is a nonylphenol initiated polyether having 17 propylene     oxide units attached

Further storage stability testing has been carried out at −10° C., ambient and +40° C. over 5-7days. This showed that the amount of additional solvent required to keep a package, showing similar IVD performance, in one phase could be reduced by up to 60% by using the present invention.

Example 9 Intake Valve Detergency

The intake valve detergency properties exhibited by the friction modifier and carrier oil combinations listed below were measured using industry standard CEC-F-05-A93 test procedure on a bench engine. The test engine was a Mercedes-Benz M 102.982 four cylinder, four stroke 2.3 litre gasoline-injection engine with a standard KE-Jettonic injection system. The test carried out involved a cyclic procedure, each cycle including the following four operating states: Stage Time (min) Speed (min-1) Torques (Nm) Power (kW) 1 0.5   800 ± 50   0 ± 2 0 2 1.0 1,300 ± 50 29.4 ± 2 4 3 2.0 1,850 ± 50 32.5 ± 2 6.3 4 1.0 3.000 ± 50 35.0 ± 2 11.0

The duration of each test was exactly 60 h with the cycle repeated 800 times. At the beginning of each test the engine was fitted with new inlet valves which were weighed before fitting. At the end of each test, and before the visual assessment and before weighing the used inlet valves, residues were cleaned carefully from the valve surface facing the combustion space. The valves were then immersed in n-heptane for 10 seconds and swung dry. After drying for 10 minutes, the valves were weighed and the increase in valve weight caused by deposits was measured in mg. During the dismantling of the valves the sticky or non-sticky appearance of the deposits formed on the valve tulip and valve stem was also evaluated. The tendency to form deposits of sticky appearance could indicate, ultimately, a tendency to the appearance of the valve stick phenomenon which is desirable to avoid.

The fuel employed in the test procedure was an unleaded gasoline meeting EN228 specification. The test compositions were added to the fuel so as to obtain a concentration of active substance (friction modifier and carrier oil) in the fuel in the amounts indicated.

Using Carrier D as carrier, at 1:1.6 ratio of friction modifier:carrier Active treat Friction Modifier IVD 150 mg/l 1000 mwt bis TEPA PIBSI IVD = 82.1 mg/valve 150 mg/l 1000 mwt mono Butylamine PIBSI IVD = 87.6 mg/valve

Using Carrier A as carrier, at 1:1 ratio of friction modifier:carrier Active treat Friction Modifier IVD 245 mg/l 1000 mwt bis TEPA PIBSI IVD = 82 mg/valve 245 mg/l 1000 mwt AEEA PIBSI IVD = 37 mg/valve

Using Carrier C at 1:1 ratio of friction modifier:carrier in a fuel of low sulphur content Active treat Friction Modifier IVD 254 mg/l 1000 mwt AEEA PIBSI IVD = 33.2 mg/valve 350 mg/l 1000 mwt AEEA PIBSI IVD = 15.5 mg/valve

Example 10 Valve Stick Performance

A series of tests was also carried out to evaluate the actual valve stick properties of various formulations. Test running was carried out on a single roll distance accumulation dynamometer manufactured by Labeco. The test engine is a regular Volkswagen Transporter 1.9-liter, 44 kW water-cooled-boxer Otto engine type 2 series with hydraulic valve filter. It is a flat four cylinder engine mounted at the rear, with a three-speed automatic transmission. The cylinder heads are dismantled after each test (one test=3 runs on the same fuel) and are cleaned with a suitable cleansing agent until metallically dean. The valve guides and valve stems are measured before each test.

The fuel used in these tests is an unleaded gasoline meeting EN228 specification.

The procedure described by DKA (Deutscher Koordinierungs Ausschuess) CEC F-16-T-96 was followed. Each cycle included the following operating states: Drive 130 km at level road load as follows: 5 km at 50 km/h 5 km at 60 km/h Stop engine - pause 10 minutes Carry out a total of 13 times to occupy 4 hours 33 minutes Switch off engine and soak to temperature for 15 h Carry out three cycles with a soak temperature of +5° C.

At the end of each engine soak phase, an engine compression test is carried out to highlight any valve which is not functioning correctly. If compression at one or more of the cylinders is less than 8 bar then the inlet valve is deemed to have been sticking in the valve guide. For the final result, with a pass at −18° C., the same cycle is used except the soak temperature is −18° C. rather than 5° C.

The test compositions are added to the fuel so as to obtain a concentration of active substance in the fuel containing additives which is specified for each example in the Table below, which gives the results obtained. Total Active Friction Friction active Modifier/ Modifier Carrier mg/l Carrier ratio Temp. Pass/fail 1000/b/TEPA D 141 1:1.6 +5° C. Fail 1000/ButA A 317 1:1.6 +5° C. Pass 1000/AEEA A 317 1:1.6 +5° C. Pass 1000/AEEA A 317 1:0.9 −18° C. Pass 1000/AEEA C 317 1:1   −18° C. Pass 1000/AEEA C 350 1:1   −18° C. Pass

Example 11 Intake Valve Detergency

The intake valve detergency properties exhibited by the friction modifier and carrier oil combinations listed have been measured using the CEC F-20-A-98 test procedure on a bench engine. The test engine is a Mercedes Benz M111 four cylinder, four-stroke 2.0 litre gasoline-injection engine with four valves per cylinder and an electronically controlled ignition and fuel injection system. The test carried out involves a cyclic procedure, each cycle including the following four operating states: Stage Time (min) Speed (min-1) Torque (Nm) 1 0.5  750 ± 50 Closed throttle 2 1.0 1500 ± 25 40 ± 2 3 2.0 2500 ± 25 40 ± 2 4 1.0 3500 ± 25 40 ± 2

The duration of each test is 60 hours. At the beginning of each test, the engine is fitted with new inlet valves, which are weighed before fitting. At the end of each test, and before weighing of the used inlet valves, residues are cleaned carefully from the valve surface facing the combustion space. The valves are then immersed in n-heptane for 10 seconds and air dried for at least 10 minutes and a maximum of 2 hours. Each valve is then weighed on a precision scale to an accuracy of at least one milligram, to determine the total weight of the valve and all its deposits.

The inlet valve deposit weight is determined by subtracting the weight of the clean intake valve that was determined before commencement of test and expressed in mg/valve.

The fuel employed was an unleaded gasoline meeting EN228 specification.

Using Carrier C as carrier, at a 1:1 ratio of friction modifier:carrier. Active Treat mg/l Friction Modifier IVD mg/valve 188 1000 mwt AEEA PIBSI 106.2 254 1000 mwt AEEA PIBSI 63.6 306 1000 mwt AEEA PIBSI 27.3

All publications mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the described methods and system of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in chemistry or related fields are intended to be within the scope of the following claims. 

1. A friction modifier represented by the formula R¹-L-N(R²)(R³) wherein R¹ is a hydrocarbyl group and has a number average molecular weight (Mn) of from 500 to 5000; L is an optional linker group; and R² and R³ are independently selected from H, a hydrocarbyl group and a bond to optional group L, wherein at least one of R² and R³ is H or a hydrocarbyl group, with the proviso that if one of R² and R³ is a hydrocarbyl group and the other of R² and R³ is H, the hydrocarbyl group does not contain a terminal amine.
 2. A friction modifier according to claim 1 wherein R¹ is a hydrocarbon group.
 3. A friction modifier according to claim 1 wherein R¹ is a branched or straight chain alkyl group.
 4. A friction modifier according to claim 3 wherein R¹ is a branched alkyl group.
 5. A friction modifier according to claim 2 wherein R¹ is polyisobutene.
 6. A friction modifier according to claim 1 wherein R¹ has a molecular weight of from 800 to
 1300. 7. A friction modifier according to claim 5 wherein R¹ is polyisobutene having a molecular weight of from 800 to
 1300. 8. A friction modifier according to claim 1 wherein group R¹ has from 10 to 200 carbons.
 9. A friction modifier according to claim 1 wherein group R¹ has from 10 to 100 carbons.
 10. A friction modifier according to claim 1 which comprises linker L.
 11. A friction modifier according to claim 1 wherein L when bonded to N(R²)(R³) provides a cyclic group of formula:

wherein e and f are independently an integer of from 0 to
 6. 12. A friction modifier according to claim 1 wherein both R² and R³ are H.
 13. A friction modifier according to claim 1 wherein at least one of R² and R³ is a hydrocarbyl group.
 14. A friction modifier according to claim 13 wherein at least one of R² and R³ is a hydrocarbyl group terminated with a moiety selected from —CH₃, ═CH₂, —OH, —C(O)OH, and derivatives thereof.
 15. A friction modifier according to claim 13 wherein at least one of R² and R³ is a hydrocarbyl group of the formula —[R⁴NH]_(p)R⁵X wherein R⁴ is an alkylene group having from 1 to 10 carbons wherein R⁵ is an alkylene group having from 1 to 10 carbons wherein p is an integer from 0 to 10; wherein X is selected from —CH₃, —CH₂═CH₂, —OH, and —C(O)OH.
 16. A friction modifier according to claim 15 wherein R⁴ is an alkylene group having from 1 to 5 carbons.
 17. A friction modifier according to claim 15 wherein R⁵ is an alkylene group having from 1 to 5 carbons.
 18. A friction modifier according to claim 15 wherein at least one of R² and R³ is a hydrocarbyl group of the formula —[(CH₂)_(q)NH]_(p)(CH₂)_(r)X wherein p is an integer from 0 to 10; wherein q is an integer from 1 to 10; wherein r is an integer from 1 to 10; and wherein X is selected from —CH₃, —CH₂═CH₂, —OH, and —C(O)OH.
 19. A friction modifier according to claim 18 wherein p is an integer from 1 to
 10. 20. A friction modifier according to claim 18 wherein q is an integer from 1 to
 10. 21. A friction modifier according to claim 18 wherein r is an integer from 1 to
 10. 22. A friction modifier according to claim 15 wherein X is selected from —CH₃, and —OH.
 23. A friction modifier according to claim 15 wherein at least one of R² and R³ is a group of the formula —(CH₂)₃CH₃.
 24. A friction modifier according to claim 23 wherein one of R² and R³ is a group of the formula —(CH₂)₃CH₃, and the other of R² and R³ is H.
 25. A friction modifier according to claim 15 wherein at least one of R² and R³ is a group of the formula —(CH₂)₂NH(CH₂)₂OH.
 26. A friction modifier according to claim 25 wherein one of R² and R³ is a group of the formula —(CH₂)₂NH(CH₂)₂OH, and the other of R² and R³ is H.
 27. A friction modifier according to claim 1 which is a polyisobutenyl succinimide.
 28. A friction modifying composition comprising: (i) a friction modifier according to claim 1; (ii) a carrier oil comprising an optionally esterified polyether.
 29. A friction modifying composition according to claim 28 wherein the polyether carrier oil has a molecular weight in the range 500 to
 5000. 30. A friction modifying composition according to claim 28 wherein the polyether carrier oil is a mono end-capped polypropylene glycol.
 31. A friction modifying composition according to claim 30 wherein the end cap is a group consisting of or containing a hydrocarbyl group having up to 30 carbon atoms.
 32. A friction modifying composition according to claim 31 wherein the end cap is or comprises an alkyl group having from 4 to 20 carbon atoms.
 33. A friction modifying composition according to claim 30 wherein the carrier oil is a polypropyleneglycol monoether of the formula:

where R⁶ is straight chain C₁₂₋₁₈ alkyl; and n is an integer of from 10 to
 30. 34. A friction modifying composition according to claim 28 wherein the friction modifier is present in an amount of from 10 to 60% by weight, based on the total composition.
 35. A friction modifying composition according to claim 28 wherein the carrier oil is present in an amount of from 10 to 40% by weight, based on the total composition.
 36. A friction modifying composition according to claim 28 wherein the weight ratio of friction modifier to carrier oil is from 0.2:1 to 5:1.
 37. A friction modifying composition according to claim 28 further comprising a solvent.
 38. A friction modifying composition according to claim 37 wherein the solvent is a hydrocarbon solvent having a boiling point in the range 66 to 320° C.
 39. A fuel additive composition comprising: (i) a friction modifier as defined in claim 1; and (ii) a carrier, diluent or solvent; which is substantially free of any detergent or friction modifier other than the friction modifier as defined in claim
 1. 40. A fuel additive composition according to claim 39 which is substantially free of any detergent and any friction modifier other than the friction modifier as defined in claim
 1. 41. A fuel additive composition according to claim 39 wherein the carrier, diluent or solvent is a carrier oil comprising an optionally esterified polyether.
 42. A fuel additive composition according claim 39 wherein the carrier, diluent or solvent is a polyether carrier oil as defined in claim
 29. 43. A fuel composition comprising (i) a fuel; and (ii) a friction modifier according to claim
 1. 44. A fuel composition comprising (i) a fuel; and (ii) a friction modifying composition according to claim
 28. 45. A fuel composition comprising (i) a fuel; and (ii) a fuel additive composition according to claim
 39. 46. A fuel composition according to claim 43 wherein the friction modifier is present in an amount, on a weight basis, of 50 to 500 ppm.
 47. A fuel composition according to claim 44 wherein the friction modifying composition is present in an amount to provide on a weight basis, from 50 to 500 ppm friction modifier and 30 to 500 ppm carrier oil.
 48. A fuel composition according to claim 43 wherein the fuel is a gasoline.
 49. A process for the reduction of friction in a combustion engine comprising the steps of: (i) dosing a fuel with a friction modifier as defined in claim 1, or a friction modifying composition as defined in claim 28, or a fuel additive composition as defined in claim 39, to provide a fuel composition; (ii) combusting the fuel composition in a combustion engine.
 50. A process according to claim 49 wherein the fuel composition is substantially free of any detergent other than the friction modifier as defined in claim
 1. 51. A process according to claim 49 wherein the fuel composition is substantially free of any friction modifier other than the friction modifier as defined in claim
 1. 52. Use of a friction modifier as defined in claim 1, or a friction modifying composition as defined claim 28, or a fuel additive composition as defined in claim 39, for reducing friction or improving detergency in a combustion engine.
 53. Use of a friction modifier as defined claim 1, or a friction modifying composition as defined in claim 28, or a fuel additive composition as defined in claim 39, for reducing friction and improving detergency in a combustion engine. 54-59. (canceled) 